Design 1, Design 3 (Computer and Video Games)
Unit 4 - 29th, 31st October 2002


This is a description of image file formats available in UnrealEd 2.0. Many things have changed since. The information given at this webpage is valid still. If you want to check our the new file formats available with UnrealTournament 2003 go to the tutorial describing the UT2003 only ! file formats.

These are sections of a 512 x 512 pixel bitmap image (left) and a 512 x 512 .pcx image:

The different qualities stem from the fact that bitmaps have a 24 Bit Colour resolution whereas ZBrush .pcx files only have 8 Bit resoulution.

One should think that the size of a texture package using imported .pcx files in Unreal is only a quarter of the size compared to one using Bitmap images. This is not so.

For reasons unknown an Unreal import of 4 Bitmaps with 512 x 512 pixels and 24 bit colour resolution once saved as a package has a file size of 2 MegaBytes. (Adding up the 768 kB x 4 results in 3072 Bytes, so gues what Unreal does with 1072 Bytes that are gone. No good I am afraid.)
An Unreal import of 4 .pcx files with 178 kB each should create a package of 712 kB, which is not the case. Unreal creates a 1.33 MB file. (Where do the additional 621 kB of information come from? Go and ask Tim Sweeny from Epic Megagames!)

Basically the tradeoff in memory consumption versus quality looks like that: You save some 30% on filesize when downgrading from Bitmap to .pcx.